Cataract is a disease in which the opacity and the pigmentation arise in the crystalline lens to thereby cause a state that the entire visual field is fogged. As for the treatment method therefor, a surgical operation is generally performed such that the clouded crystalline lens is removed and an intraocular lens (IOL) is inserted into and installed in the capsule of crystalline lens. Most of the materials for the intraocular lens, which are used for the treatment, are based on acrylic or silicon polymer. In particular, for example, polymethyl methacrylate (PMMA) has been hitherto used.
However, the intrinsic crystalline lens has a property that the ultraviolet light is not transmitted therethrough. On the contrary, the ultraviolet light is transmitted through the conventional polymer for the intraocular lens. Therefore, there is a risk that the retina may be damaged.
Further, the intrinsic crystalline lens is slightly yellowish, which has a property that a part of the light in the blue region is suppressed from being transmitted. However, the light in the blue region is approximately completely transmitted through the conventional transparent polymer for the intraocular lens. Therefore, the patients complain the glare in many cases after the operation for inserting the intraocular lenses. Further, there has been also a risk that any disease originating from the retina including, for example, macular degeneration may be caused when the light in the blue region, which has the short wavelength and the high energy, arrives at the interior of the eye.
In view of the above, the material for the intraocular lens is required to have the ability to absorb the ultraviolet light and the coloring brought about by a yellow-based colorant. In recent years, in view of the safety, an UV absorber monomer and/or a yellow-based colorant monomer is/are copolymerized in many polymers for the intraocular lens. Various monomer compounds as described above have been hitherto developed (Patent Documents 1 to 4). Monomer compounds, which are copolymerizable with other monomers for the intraocular lens material, have been also developed, each of which has a chromophore such as an azo group or the like and a UV-absorbing portion such as a benzophenone skeleton or the like in one molecule (Patent Documents 5 and 6).